Some cancer patients die from the effect of the cancer-associated cachexia rather than the tumor per se. Because cachexia and progressive weight loss can occur in patients with quite small tumors, it is currently believed that these effects are the results of a systemic effect of the tumor on the host. The objective of this proposal is to test the hypothesis that a tumor-induced amino acid imbalance is responsible for some of the effects of a tumor on the host. A totally parenterally nourished tumor-bearing rat model will be given one of five parenteral diets containing different amino acid mixtures. The three main assays to be used are: (1) N retention, (2) glucose turnover, and (3) muscle protein fractional synthesis rates.